ZT ~ 3.5: Fifteen Years of Progress and Things to Come

Fifteen years ago prospects for improving thermoelectric efficiency seemed slight and little evidence for ZT>1 was known [1]. Today, reports of ZT~2 are widely known, startup companies are forming based on this progress and enthusiasm for further advances is widespread. The enthusiasm is not without basis: at least one credible experimental study estimates ZT~3.5 [2] and at least one credible source estimates the bound may be as large as ZT~20 [3]. Thermoelectric applications have changed dramatically as well, with widespread commercial acceptance of products ranging from picnic baskets to automobile seats. Yet basic research advances have yet to impact applications, which thrive in spite of the basic R&D rather than because of it. This paper discusses some of the key developments, both technical and programmatic, which have driven recent progress and speculates on some developments which may be useful, possible and/or likely to drive progress forward.

http://cvining.com/system/files/articles/vining/Vining-ECT-2007.pdf